class_docstr: Type specifically made for labels that are mapped to a key.
  
  Parameters
  ----------
  path
      Path to a file that has multiple classes separated by new line character.
      Index of the line will be considered as the key for each class. This parameter
      is mutually exclusive to `classes` parameter
  classes
      A list, tuple or a dict of classes. If it's list or a tuple, index of the
      class, is the key. If it's a dictionary, the key must be an integer
code: def serialize(self, key: Tensor) -> str:
      return self.classes[key.item()]
  
file_path: lightning-flash/src/flash/core/serve/types/label.py
imports: from dataclasses import dataclass, field
  from pathlib import Path
  from typing import Dict, List, Tuple, Union
  import torch
  from torch import Tensor
  from flash.core.serve.types.base import BaseType
label_desc: Use image node_id 3 for calling the Label obj's underlying member method code with example usage: obj.serialize(key) and returns: self